Why are antibiotics not effective for viral diseases?

$(a)$ What is immunisation?
$(b)$ Categorise the following into acute,chronic,infectious,or non-infectious diseases: Typhoid,$TB$,Goitre,Elephantiasis.

You are aware of the $Polio$ $Eradication$ $Programme$ in your city. Children are vaccinated because:

Making anti-viral drugs is more difficult than making anti-bacterial medicines because

Who discovered the 'vaccine' for the first time? Name two diseases which can be prevented by using vaccines.

About a hundred years ago,when smallpox persisted,a group of people who had this disease earlier and had survived it had no chance of suffering from it again. So,having the disease once was a means of preventing subsequent attacks of the same disease.
$(a)$ Why does this happen? Explain.
$(b)$ We can 'fool' the immune system. Clarify.
$(c)$ Name this principle of prevention of diseases.